Hair care device and method for enhancing uptake of a topical in hair

ABSTRACT

A hair care device for enhancing uptake of a topical in hair. The hair care device comprises a topical delivery unit for applying the topical to the hair surface, an ultrasound generator ( 103 ) for generating ultrasound at a frequency exceeding 15 MHz, wherein an ultrasound intensity is in a range between 2 W/cm 2  and 100 W/cm 2 , and an ultrasound transducer ( 105 ) for applying ultrasound to the topical and/or the hair surface to enhance uptake of the topical by the hair.

FIELD OF THE INVENTION

The invention relates to a hair care device and method for enhancinguptake of a topical in hair.

BACKGROUND OF THE INVENTION

Applications of topicals in hair include moisturization and protection.For example, excessive heat treatments of hair can cause a reduction inmoisture content and potentially lead to hair damage or even breakage.Often it is advised to use a heat protection topical to safeguard thehair from excessive heat or to moisturize the hair when it is damaged.This resonates with consumers because they want to make their hairhealthier and more resistant to damage from styling. The appliedtopicals can be in the form of oil (e.g. Argan oil), or watery solutionsthat contain a mixture of ingredients. These solutions are often appliedby hand into the hair pre-styling but the downside is that the user hasneither control over how well the topical is distributed on the hairs,nor how well the topical penetrates into the hair structure. Solutionscan also be applied through appliances or onto appliances during stylingto enhance protection to heat based styling or to moisturize the hair.

U.S. Pat. No. 5,267,985 provides a method and apparatus for enhancingthe diffusion of a substance to a local area of material or tissue byproviding ultrasonic energy to the substance and material in two or moredistinct frequencies simultaneously. Each of the distinct frequencies ofultrasonic energy is chosen to enhance permeation of the substancethrough one or more diffusion rate-limiting sections of the material.The preferred frequency range for each signal is from 100 Hz to 100 MHz.Preferred combinations for two-frequency methods include 1 MHz & 3 MHz;3 MHz & 9 MHz, and 5 MHz & 15 MHz. A first frequency may be selected toenhance diffusion of the substance through a first portion of thematerial. In that case, the material may be living tissue and the firstportion of the material may be a stratum corneum layer of skin. In thatcase, the first frequency may lie in the range of 10 kHz to 100 MHz.This prior art document is primarily concerned with providing ultrasonicenergy to living tissue in two or more distinct frequenciessimultaneously in which a first portion of the material is a diffusionrate limiting membrane, so that a suitable first frequency is needed toenhance permeation of the substance through that first portion; hair(which is not a living tissue) is not discussed in this prior artdocument.

US 20060272665 discloses an ultrasonic hair treatment device to applyultrasonic vibrations to a user's hair for enhancing the penetration ofa hair treatment composition into the hair. A piezoelectric transduceris supplied with an electric power and is controlled by a controller toproduce vibrations of 500 kHz to 10 MHz frequency at a power of 0.1 to 5W/cm.

WO 99/51295 discloses a system for enhancing and improving thetranscutaneous or transdermal delivery of topical chemicals or drugs. Adisposable container contains a substantially sterile unit dose of anactive agent adapted for a single use in a medical treatment. The unitdose is formulated to enhance transport of the active agent throughmammalian skin when the active agent is applied to the skin and the skinis exposed to light and/or ultrasound defined by at least one specificparameter. Preferred ultrasound parameters may be determined inaccordance with both efficacy and safety requirements. For example, onepreferred range for lower frequency ultrasound may be between about 25kHz and about 3 MHz at about 0.5-2.0 W/cm² (either continuous or pulsed,using about a 20-25% duty cycle if pulsed). A preferred setting withinthis range may be at about 1.0 MHz at about 2.0 W/cm², with a continuouswave beam and a treatment time of between about five and ten minutes. Apreferred setting within this range for non-continuous beam (i.e. pulseddelivery) may be at about 1.0 MHz at about 0.2-0.5 W/cm² with a 20-25%duty cycle with around a 2.0-20.0 ms “on” cycle and a treatment time ofabout five and ten minutes. One preferred range for higher frequencyultrasound may be between about 3 MHz and about 16 MHz at about 0.2-1.0W/cm² (either continuous or pulsed, using about a 20% duty cycle ifpulses), with a treatment time of between about one and twenty minutes.A preferred setting within this range may be at about 10 MHz at about0.2 W/cm², with a continuous treatment time of between about five andtwenty minutes. A preferred embodiment may be useful to specificallystimulate (or inhibit) the growth of hair or other skin appendages (suchas nails, etc.). A preferred embodiment, may also be useful to stimulatethe growth, or re-growth, of fine vellus or dormant or inactive hairs(e.g. to treat hair loss, for example). For example, the effectivenessof Rogaine or similar drugs used in the treatment of male patternbaldness may be enhanced. It is noted that the above ultrasoundparameters are disclosed in a paragraph between two paragraphs relatingto skin treatment; no ultrasound parameters are disclosed specificallyin relation to hair treatment.

SUMMARY OF THE INVENTION

It is, inter alia, an object of the invention to provide an improvedhair care device and method for enhancing uptake of a topical in hair.The invention is defined by the independent claims. Advantageousembodiments are defined in the dependent claims. Advantageous featuresof the hair care device are also advantageous features of the hair caremethod.

Embodiments of the present invention feature ways to enhance the safeand effective uptake of topicals in the hair structure by usingultrasound (15-50 MHz) induced cavitation. This provides a simple andlow-cost solution to enhance topical uptake by the hair structure beforeor during styling and thereby reducing the risk on hair damage. Thelower frequency limit of 15 MHz has been chosen to trigger the largestinclusions to be activated on the hair surface. The upper frequencylimit of 50 MHz has to do with the fact that, when frequency increases,the power needed to trigger smaller inclusions will increase as well. 50MHz is preferred as the upper frequency limit since at this frequency wecan still find a reasonable combination of duty cycle and treatment timeto limit thermal issues.

Embodiments of the present invention provide enhanced topical uptake forsmall and large tresses of hair. This is based on the insight that theindentation depth of cuticles is 0.3-2 μm, resulting in poor hairpermeability for frequencies in the kHz range up to 10 MHz. Inphonophoresis, the increase in tissue permeability is mostly due tocavitating bubbles: therefore, low frequencies (20-100 kHz) are usuallyemployed. In this context, acoustic cavitation refers broadly to violentoscillations of pre-existing gas inclusions. However, the typical sizeof the indentation depth between cuticle scales on a healthy andundamaged/untreated hair surface is about 0.3-0.5 μm, i.e. approximately1 cuticle cell. When stressed (particularly if bent) or damaged, theindent can be much larger, in the order of 1-2 μm. When hair is wet, wemay expect gas bubbles to be trapped in these indentation depths,meaning that available gas bubbles for cavitation activity will probablybe in the range of 0.3-2 μm. Therefore, using a frequency range of 15-50MHz should ensure gentle cavitation of trapped gas bubbles in damagedand undamaged cuticle scales. The power required for inertial cavitationincreases significantly at higher frequencies (from about 2 W/cm² at 1MHz to about 100 W/cm² at 50 MHz). Higher power usage leads to highertemperature increases per second. If cavitation is used to increase thepermeability of cuticle scales and to increase moisture uptake, cuticlescales should be closed after treatment (for instance using aconditioner or simply by surface moisturization) to avoid fast moistureloss after treatment. Alternatively, cavitation may be set at a verygentle reversible level, limiting the damage to cuticle: also to thispurpose, the choice of higher frequencies (MHz range) will bebeneficial.

If hair is exposed to ultrasound at a specific frequency and intensity(or pressure), inertial cavitation will be induced in a range of bubbleswith different radii. Assuming an input ultrasound of twice the pressurethreshold to induce cavitation, a conservative assumption consideringappropriate safety ranges, it is possible to derive a range of initialbubble radius that undergoes inertial cavitation at differentfrequencies. The inventors have recognized that this range decreaseswith increasing frequency, and that at low frequencies, cavitation mayoccur in gas bubbles larger than the range of bubbles in hair cuticle.This should be avoided since this may cause violent cavitation, forminguncontrolled shock waves that may damage hair structures. At frequenciesbetween 20 MHz and 50 MHz, the generated inertial cavitation is confinedto the bubbles with radii within the range of the dimension of the haircuticle indentation depth. The inventors have thus recognized that it ispreferred to use ultrasound frequencies within the range of 20 MHz to 50MHz to induce selective cavitation in hair cuticles for improved topicaluptake.

Embodiments of the present invention provide a safer treatment, ascavitation at low frequencies requires less energy than at higherfrequencies and the range of bubbles excited tends to be larger.Ultrasound at megahertz frequencies will create less inertial cavitation(mechanical index cavitation). The higher the frequency the less violentcavitation is created, thereby reducing the likelihood of mechanicallydamaging the hair structure.

Embodiments of the present invention provide ease of use, simpleexecution, low-power requirements, a small footprint, e.g. a smallhandheld device.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first embodiment of the invention;

FIG. 2 shows a second embodiment of the invention; and

FIG. 3 shows a third embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention provide a handheld, preferablycordless system which generates ultrasound to treat hairs coated by atopical for enhanced uptake of said topical. The ultrasound treatment isapplied through direct contact with the topical covered hairs,preferably by clamping a tress of hair.

FIG. 1 shows an ultrasound generator 103 which generates fixed orvariable low-voltage ultrasound pulses, with frequency, voltage andpulse duration controlled by a controller 102 depending on treatmentsettings selected through a user interface 101. An acoustic amplifier104 achieves the required output acoustic intensity. An ultrasoundtransducer 105 projects the ultrasound into the topical that is appliedon to the hair surface 107. A practical embodiment will further featurea topical delivery unit for applying the topical to the hair.

Piezoelectric crystals (PMUT) are used to produce ultrasound (>20 kHz).Non-piezoelectric techniques like Capacitive Micro-machined UltrasonicTransducers (CMUT) can be used for higher frequencies (typically up to100 MHz) and can be used with this invention.

In a preferred embodiment the ultrasound transducer is embedded in thehair interface. It features a clamp to provide optimal contact with thehairs. The treatment clamps will be positioned close together inoperating mode, where the distance between the clamps ideally should besmaller than one wavelength to promote uniformity, increasing theamplitude of the signal and time to result. Especially at higherfrequencies this becomes an option since the energy is absorbed veryquickly and might not even reach the opposed clamp. This will enablelower power usage and increase uniformity while enhancing cavitation toachieve better penetration into the hair structure. To minimize unwantedthermal effects the ultrasound could be configured in pulsed mode with1% duty cycle and a maximum treatment time of 4 s to stay below amaximum increased temperature threshold of 100° C.

FIG. 2 illustrates such a preferred embodiment, featuring a controller202, an ultrasound generator and amplifier 203, a topical delivery unit206, comb teeth 209 provided with ultrasound transducers 205, and ahandle 211. The topical delivery unit 206 applies the topical to asurface of the hair structure. The controller 202 controls a level ofultrasound intensity and a predetermined duty cycle for applying thelevel of ultrasound intensity for improved topical uptake in a hairstructure. The ultrasound transducers 205 have a topical contact surfacefor applying ultrasound energy to the topical. Preferably, theultrasound is applied to the topical close or on the hair surface. Sothe ultrasound applied to the topical will also interact with the hair.The controller may have a user interface.

One alternative embodiment features two or multiple ultrasoundtransducers instead of one. Having two ultrasound sources or an array ofultrasound transducers opposed to each other in both clamps of thedevice will decrease the time to result and probably create constructiveinterference. If the distance between the clamps is not predeterminedthe chance of destructive interference is large. This will not happen ifthe distance between the closed clamps is exactly multiple times thewavelength of the frequency used or (2N+1)*lambda/4 for multipleultrasound sources.

FIG. 3 illustrates such an alternative embodiment, featuring ultrasoundtransducers 305A and 305B on respective clamps 313 of a hairstraightener, a controller 302, an ultrasound generator and amplifier303, a topical delivery unit 306, and a swivel mechanism 315.

Preferably, the ultrasound intensity is in a range between 2 W/cm² and100 W/cm².

Preferably, the predetermined duty cycle is in a range between 1% and50%. The inventors have found that at an ultrasound frequency of 20 MHz,a preferred upper limit of the duty cycle is 12.5%, while at anultrasound frequency of 50 MHz, the preferred upper limit of the dutycycle is 5%.

Preferably, the hair care device comprises an array of ultrasoundtransducers.

Preferably, the controller comprises a look-up-table for determining thelevel of ultrasound intensity and the predetermined duty cycle for aspecific hair type or topical.

Preferably, the hair care device comprises a sensor connected to thecontroller, the sensor being configured for sensing a parameterassociated with the properties, e.g. temperature, moisture, of thetopical and the hair. Preferably, the sensor is selected from a listcomprising a temperature sensor for sensing a temperature increasecaused by the application of ultrasound, an optical sensor for sensing achange of the optical properties e.g. scattering, reflectance, caused bythe application of ultrasound, an acoustical sensor for sensing a changeof the acoustic properties, e.g. acoustic impedance, speed of sound,caused by the application of ultrasound, and an electrical sensor forsensing a change in electrical properties, e.g. radio frequencyimpedance, capacitance, caused by the application of ultrasound.

Preferably, the controller is configured to stop the applying ofultrasound to the topical before a predetermined temperature limit isreached, the predetermined temperature limit being preferably 100° C.and more preferably 50° C. Alternatively, in dependence on thetemperature, the intensity and/or the duty cycle of the ultrasound couldbe adjusted so as to prevent the temperature from becoming too high.

Preferably, in use the transducer is in physical contact with thetopical and/or the hair and positioned at a distance of preferably morethan 0.3 cm, more preferably more than 1 cm, away from the skin surface.This distance ensures that the ultrasound application will have itsintended positive effects without unintended negative effects to hairhealth. To this end, the hair care device preferably is provided with asuitable distance holder to ensure this minimum distance between thetransducer and the skin surface.

One alternative embodiment features systems and methods that initiate afeedback loop to measure attenuation of ultrasound in the hair structureto determine moisture content and adjust settings accordingly.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.The word “comprising” does not exclude the presence of elements or stepsother than those listed in a claim. The word “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.In the device claim enumerating several means, several of these meansmay be embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage.

1. A hair care device for enhancing uptake of a topical in hair, thehair care device comprising: a topical delivery unit for applying thetopical to the hair surface; an ultrasound generator for generatingultrasound at a frequency exceeding 15 MHz, wherein an ultrasoundintensity is in a range between 2 W/cm² and 100 W/cm²; and an ultrasoundtransducer for applying ultrasound to the topical and/or the hairsurface to enhance uptake of the topical by the hair.
 2. The hair caredevice as claimed in claim 1, wherein the ultrasound generator isarranged to generate ultrasound at a frequency not exceeding 50 MHz. 3.The hair care device as claimed in claim 1, wherein the ultrasoundgenerator is arranged to generate ultrasound at a frequency of at least20 MHz.
 4. The hair care device as claimed in claim 1, wherein apredetermined duty cycle of the ultrasound is in a range between 1% and50%.
 5. The hair care device as claimed in claim 3, wherein apredetermined duty cycle of the ultrasound does not exceed 12.5%, andpreferably does not exceed 5%.
 6. The hair care device as claimed inclaim 1, wherein the hair care device comprises an array of ultrasoundtransducers.
 7. The hair care device as claimed in claim 1, furthercomprising a controller for controlling a level of ultrasound intensityand a duty cycle for applying the ultrasound intensity.
 8. The hair caredevice as claimed in claim 7, wherein the controller comprises alook-up-table for determining a level of ultrasound intensity and a dutycycle for a specific hair type or topical.
 9. The hair care device asclaimed in claim 7, wherein the hair care device comprises a sensorconnected to the controller, the sensor being configured for sensing aparameter associated with properties of the topical and/or the hair. 10.The hair care device as claimed in claim 9, wherein one or more sensorsare selected from a list comprising: a temperature sensor for sensing atemperature increase caused by the application of ultrasound, an opticalsensor for sensing a change of optical properties e.g. scattering,reflectance, caused by the application of ultrasound, an acousticalsensor for sensing a change of the acoustic properties, e.g. acousticimpedance, speed of sound, caused by the application of ultrasound, andan electrical sensor for sensing a change in electrical properties, e.g.radio frequency impedance, capacitance, caused by the application ofultrasound.
 11. The hair care device as claimed in claim 7, wherein thecontroller is configured to stop the applying of ultrasound to thetopical and/or the hair before a predetermined temperature limit isreached, the predetermined temperature limit being preferably 100° C.and more preferably 50° C.
 12. The hair care device as claimed in claim1, further comprising a distance holder for positioning the transducerat a distance of more than 0.3 cm, preferably more than 1 cm, away froma skin surface.
 13. A hair care method of enhancing uptake of a topicalin hair, the hair care method comprising: applying the topical to thehair surface; generating ultrasound at a frequency exceeding 15 MHz,wherein an ultrasound intensity is in a range between 2 W/cm² and 100W/cm²; and applying ultrasound to the topical and/or the hair surface toenhance uptake of the topical by the hair.
 14. The hair care method asclaimed in claim 13, wherein the ultrasound is applied to the topicalclose to or on a hair surface.